Image tube



C. J. YOUNG ETAL IMAGE TUBE Filed March 30, 1955 rw'ONJl- Feb. 24, 1959United States Patent O IMAGE TUBE 'Charles J. Young and George A.Morton, Princeton, N. J

assignors to Radio `Corporation of America, a corporation of DelawareApplication March 30, 1953, Serial No. 345,274

7 Claims. (Cl. 315-10) This invention relates to image tubes, ordevices. In particular, this invention relates to electron-image tubesthat are particularly adapted to high speed intelligence transmittingsystems.

For many purposes it is desirable to have a means to select a portion ofa visible image, orient this selected portion of the visible image in agiven manner, and reproduce the information obtained. On example of thisis to transform information that is contained on a teletypewriter tapeinto written information. Another example is for decoding codedmessages.

Various mechanical devices have been designed to convert some type ofcoded information into de-coded infomation. However, these mechanicaldevices, such as teletype printers, have the disadvantage of being slowin peration Various electrical devices have overcome the slow movementinvolved in mechanical devices but these electrical devices have had thedisadvantage of not permitting a complete message to be printed at onetime.

While still other electrical devices have provided a means to reproducea complete message at one time, these devices incorporate the scanningof a character by an electron beam and do not provide high deiinition inthe final printed message. Some of these electrical devices have alsobeen limited by the disadvantage of not being able to interchange thematrix containing the characters scanned in the device withoutdisassembling the envelope.

It is therefore an object of this invention to provide a new andimproved image device, or tube.

Another object of this invention is to provide a new and novel imagedevice that eliminates the function of scanning in the formation of acharacter by an electron beam.

A further object of this invention is to provide a novel image devicehaving means for selecting from a font of characters certain ones andreproducing the selected characters at an extremely rapid rate in apredetermined manner.

A still further object of this invention is to provide a new and novelimage device that selects particular portions of an image and reproducesthe selected portions in a re-arranged relationship with respect to eachother.

A still further object of this invention is to provide a new and novelimage device utilizing a font of characters from which a signal isselected that is readily changeable with other fronts to provide adiierent coding or type face.

A still further object of this invention is to provide an improved imagedevice that will produce a complete message on the face of the tube, atan extremely fast speed, that is the exact image of what atele-typewriter would print if controlled from the same tape.

In the embodiments of the invention shown, there is provided an electronimage device comprising an evacuated elongated envelope having aphoto-sensitive cathode mounted in one end of the envelope and in theother end of the envelope a target electrode that converts electronimages into visible images. Intermediate these electrodes are providedvarious accelerating electrodes to provide acceleration to the electronimages. Intermediate the photo-sensitive cathode and the targetelectrode is pro vided an apertured electrode. Adjacent the envelope arevarious coils and yokes for selecting a particular portion of theelectrode image from the photo-sensitive cathode, focusing the selectedportion in the aperture in the apertured electrode, and positioning thisportion as a visible image in a desired manner on the target electrode.This information may then be viewed or photographed, etc.

The novel features which are believed to be characteristic of theinvention, are set forth with particularity in the appended claims. Theinvention itself will best be understood from the following descriptionstaken in conjunction with the accompanying drawings wherein likereference characters designate similar elements throughout the severalviews and in which:

Figure 1 is a sectional view of a new and novel image device constructedin accordance with this invention;

Figure 2 is a View of a mask or matrix which may be used with thisinvention; and

Figure 3 is a sectional view of a preferred embodiment of a new andnovel image device constructed in accordance with this invention.

Referring particularly to Figure l, there is shown a sectional view ofan image device, or tube, 10 comprising an elongated envelope 11 havingan exhaust tube 12. In one end of the elongated envelope 11 is asemi-transparent photo-emissive cathode 14 having a lead-in 15 connectedthereto. Any of the conventional photo-cathode materials may be used, anexample of which is caesium antimony. When the photo-cathode material isused, the antimony is applied first and then the caesium may be appliedin vapor form to the antilnony by means of the exhaust 12.

Inside the elongated envelope 1l is an accelerating electrode 16 havinga lead-in 18 connected thereto. The accelerating electrode 16 is held inplace within the envelope 11 by means of sealing the lead-in 18 throughthe envelope 11 and spot welding the electrode and lead-in. Of courseother conventional means may be used to support the acceleratingelectrode 16. The end of the accelerating electrode 16 that is adjacentthe photo-sensitive cathode 14 contains an evaporator electrode 17 toevaporate the caesium vapor as is well known in the art.

Adjacent the other side of accelerating electrode 16 is a baille, orapertured electrode, 24 that is sealed across the entire tube structure.The apertured electrode 24 has a lead-in 25 connected thereto, and iscomposed of any conductive material. The single aperture 19 in aperturedelectrode 24 is substantially centrally located and may be either round,square, or any other desired conguration. The size of aperture 19 mayvary as will be explained hereinafter.

On the target side of apertured electrode 24 are other acceleratingelectrodes 26, 32, and 34 having lead-ins 27, 33, and 3S respectively.These accelerating electrodes are also spot welded to their respectivelead-in connections for support purposes.

In the other end of the elongated envelope 11 is an anode, or targetelectrode, 36 comprising iluorescent screen with an aluminum backinghaving a lead-in 37 connected thereto. The anode 36 may be any of theconventional fluorescent screens of either of the long or shortpersistent type depending upon the operating characteristics that aredesired. An example of a short persistent screen is calcium magnesiumsilicate mixed to produce a desired white light with zinc beryliumsilicate. An

example of a long persistent screen is a layer of zinc cadmium sulfideover a layer of zinc sulfide. It should be understood that othermaterials may be used for the fluorescent screen.

Adjacent the portion of the elongated envelope 11 containing theaccelerating electrode 16 is a character selection, or deflection, yoke20 having lead-ins 21 connected thereto. Surrounding the characterselection yoke 20, and the envelope 11, is a focusing coil 22 havingleadins 23 connected thereto. The character Selection yoke 20 includescoils for both the horizontal and vertical components as is well knownin the art.

Surrounding the envelope 11 in the vicinity of acceler ating electrodes26 and 32, as shown, is a character positioning yoke 28 havingconventional leads 29 connected thereto. Surrounding the characterpositioning yoke 28 is a focusing coil 30 having leads 31 connectedthereto. It should be understood that electrostatic, in place ofelectromagnetic, deflection systems may be used in connection withdevice as is well known in the art.

The general operation of the device 10 is as follows: when a visibleimage is directed on the photo-sensitive cathode 14 by means of a lightsource 13 and the mask of characters 39 (Fig. 2), the image will causeelectrons to be emitted from the different areas of the photo sensitivecathode 14 in proportion to the light reaching the photo-cathode. Theentire electron image is accelerated toward the target electrode 36 bymeans of the accelerating electrodes 16, 26, 32, and 34. The vastmajority of the entire electron image that is accelerated toward theanode 36 will strike the bathe, or apertured electrode, 24 and onlythose that pass through aperture 19 will reach anode 36 if no otherelectrical or magnetic forces are applied to the electron stream.

We use the focusing coil 22 to maintain the entire electron image in thesame relationship as that produced by cathode 14 so that it will strikeeither the apertured electrode 24, or the aperture 19. In other words,the focusing coil 22 maintains the electron image in focus at theaperture 19 in the same form as when originally produced. The characterselection yoke dellects the entire electron image so that only a desiredportion of the entire electron image is passed through aperture 19 at agiven instant. By varying the currents through the character selectionyoke 20 any particular portion of the electron image amy be passedthrough the aperture 19 while all other portions of the image areeliminated by the conductive properties of apertured electrode 24.

The focusing coil 30 maintains the selected portion of the electronimage, i. e., the portion that passes through aperture 19 in the samerelationship throughout the path from the aperture 19 to the anode 36.The element positioning yoke 28 positions any selected portion of theelectron image on the anode 36. The operation of image device 10, aswell as examples of potentials, will be described more fullyhereinafter. A system for operating this type of image device, i. e.,feeding signals thereto, is described in an application of Charles I.Young, Serial Number 187,879 filed October 2, 1950, now U. S. Patent No.2,807,663, and assigned to the same assignee as the present invention.

Referring now to Figure 2, there is shown a mask 39 that is adapted tobe used in connection with this invention by focusing a light image 13(see Fig. l) of this mask 39 on the photo-emissive cathode 14. As shown,the mask 39 includes as characters the entire alphabet, the numbers 0-9,and other standard symbols. The characters, numbers and symbols may besubstantially transparent so that light from source 13 will passtherethrough. When a light image of a mask 39 of this type is projectedon the photo-emissive cathode 14, the cathode 14 produces an electronimage representative of the light image of the entire mask 39. Theaccelerating electrode 16 accelerates this electron image toward thebaille,

or apertured electrode 24. The electron image is maintained throughoutthe path from the photo-cathode 14 to the apertured electrode 24 bymeans of focusing coil 22. In other words, the electron image ismaintained in the same form as when originally produced.

The dellection, or selection, yoke 20 selects the electron image of anyparticular character, from the electron image of the mask 39, andlocates the selected electron image for the particular character in theaperture 19 in apertured electrode 24. By changing the currents throughthe selection yoke 20, any of the characters of the electron image ofthe mask 39 are focused into the aperture 19. This selection involvesboth horizontal and vertical deflection of the entire image formed bythe electron beam. The selection of different characters from theelectron image can occur at an extremely fast rate of speed. The onlylimitation upon the rate of changing from one selected character toanother is the time element required for changing the current throughthe selection yoke 20.

Once a particular character is selected, and the electron image of thischaracter is focused into aperture 19, the focusing coil 30 maintainsthe electron arrangement of this selected character between theapertured electrode 24 and the anode, or target electrode, 36. Thisselected character is accelerated toward the target electrode 36 bymeans of the potentials applied to the accelerating electrodes 26, 32,and 34.

When it is desired to place the selected characters in a particulararrangement, currents are applied to the positioning yoke 28 to positionthe area of impact of the selected electron images on the targetelectrode 36. Thus, by proper co-ordination between the currents appliedto the selection yoke 20, and the positioning yoke 28, material may belocated on the target electrode 36 in any form desired.

Electrode 24 may be pulsed to a negative potential with respect tocathode 14 if it is desired to bias olf the image. This, for example,may be done during the time the character is rbeing moved. There areother applications of the tube 10 where this may be required.

When the selected portion of the electron image passes through device10, it spirals to some extent. One method of correcting this in thefinal image is to twist the mask 39 so that the original light image istwisted but the nal image is properly arranged.

When the information transmitted is to be observed in a visual manner, along persistence target screen is desirable. However, in order toutilize the potentially high speed of the device, a relatively shortpersistence screen is utilized. One method of utilizing the fastresponse of the device is to photograph each frame of information duringthe time when it is being sent through device 10.

A very excellent method of transforming teletyped information intowritten information is provided. When information is in the form of atele-typewriter tape, each line on the tape, i. e., each character, maybe adjusted to develop particular currents in both the selection andposition yokes so that this information can be quickly recorded on aphotographic lm as written information. When the pattern of perforationfor each character has been altered, according to a code, the messagecan still be decoded in the process of presentation by substituting anappropriate mask, i. e., a mask with a different arrangement of thecharacters. In other words, any change in the perforation code can bematched by a change in the mask to present decoded messages.

Referring now to Figure 3, there is shown a cross-sectional view of apreferred embodiment of this invention comprising an elongated envelope43 having an expanded end 43'. In the smaller end of the elongatedenvelope 43 there is a photo-cathode 45. Extending from adjacent thephoto-cathode 45, along the envelope walls, there is an acceleratingelectrode 46. Connected to accelerating electrode 46 is a conductor 44that extends along the envelope 43 in the conventional manner. Theaccelerating electrode 46 is htld in place by conventional means such assprings 56 as shown. Adjacent the other end of accelerating electrode 46there is a baliie, or apertured electrode, 47 having a single aperture48 therein.

Adjacent the apertured electrode 47 is a cylindrical deceleratingelectrode 49. Adjacent the decelerating electrode 49 is an acceleratingelectrode S0 having a cone shaped end. The electrodes 49 and 50 alsohave conventional lead-ins and supports. The reason that it is preferredto operate electrode 49 as a decelerating electrode is to preventsecondary emission from edge of aperture 48 in the apertured electrode47. When this occurs there is a halo eiect around the characters on thetarget 51. The cone 50 opens into the expanded portion 43' of theenvelope 43. This expanded portion 43 permits the use of a large sizescreen. On the inner surface of the expanded portion 43' of the envelope43 is an aluminized fluorescent screen 5l. The fluorescent screen 51having an aluminum backing has a conventional lead-in 58 connectedthereto. The screen 51 may be applied to the end of envelope 43 byconventional methods.

One method of enlarging the size of the image on the target 51 is bychanging the position of the focusing coil as is well known in the art.Another method is to project larger size light images through thedevice.

Surrounding the photo-cathode end of envelope 43 is a characterselection, or detiection, yoke 52 as shown. Surrounding the selectionyoke 52, is a focusing coil S3. Surrounding the envelope 43, adjacentthe expanded end 43 is a character positioning, or deflection, yoke 54.Surrounding the character positioning yoke S4 is a second focusing coil55.

The currents that are applied to the various yokes to select aparticular character and position the selected character will dependupon several fa'ctors as the size of envelope 43, the potentials appliedto the various electrodes, etc., therefore specic examples will not begiven. An example of the various electrode potentials for the deviceshown in Figure 3 is as follows: assuming the photo-cathode 45 is atground potential; apertured disk 47, and the accelerating electrode 46,could be at a potential of about 150 volts positive. The deceleratingelectrode 49 could be approximately 60 volts positive since it ispreferred that this accelerating electrode have a potential that is lessthan the potential of apertured electrode 47, in order to preventsecondary emission from the edge of the aperture 48 in the aperturedelectrode 47. The accelerating electrode and cone 5U may have apotential of 5,000 volts positive and the screen may have a potential of20,000 volts positive. These potentials are not intended to be limitingbut are shown merely to give one example of successful operatingconditions.

The size of aperture 48 is preferably only slightly larger than the sizeof an electron image of a particular character of the matrix 39. It hasbeen found that aperture sizes of 1A; inch in diameter operate verysatisfactorily. The aperture may also be of some configuration otherthan circular, and would intentionally be so designed for particularmatrices.

For certain types of operation it may be desired to have a larger sizedaperture 48. When this is done pulses may be applied to aperturedelectrode 47 to result in various disconnected images of particularinformation similar to the frames of a moving picture. For applicationsof this sort an aperture 48 size of 1A inch in diameter is satisfactory.

The operation of the device shown in Figure 3 is similar to theoperation of the device shown in Figure l. Generally the operation is asfollows: a light image of transparent characters on the matrix 39 isprojected onto photo-cathode 45 by means of light source 13 and aportion of the electron image formed by the light image is selected bymeans of the current through the selection coil 52. The selected portionis passed through the aperture 48 in apertured electrode 47 and ispositioned on the target electrode 51 by means of the current throughthe positioning coil 54.

While there have been described and illustrated specic embodiments ofthe invention, it will be obvious that various changes and modificationsmay be made therein without departing from the field of the inventionwhich should be limited only by the scope of the appended claims.

We claim:

l. An image device comprising an elongated envelope, means mountedwithin one end of said envelope for producing an electron image of lightradiation from an object, means mounted within the other end of saidenvelope for producing a visible image representative of said electronimage, said last named means being substantially larger than said firstnamed means, an apertured electrode intermediate said tirst mentionedmeans and said second mentioned means, focusing means for focusing saidelectron image, selection means for selecting a portion of said electronimage and projecting said portion through said apertured electrode,focusing means for focusing said selected portion, and positioning meansfor positioning said selected portion on said second mentioned means.

2. An image device comprising an elongated envelope, a photo-sensitivecathode within one end of said envelope and adapted to release anelectron image, a target electrode at the other end of said envelope,said target electrode being substantially larger in electron receivingarea than said photo-sensitive cathode is in electron emitting area, anapertured electrode intermediate said ends of said envelope, meansadjacent said one end of said envelope for selecting a portion of saidelectron image and directing said portion through said aperturedelectrode, and deliecting means adjacent said other end of said envelopefor deiiecting said selected portion on to selected areas of said targetelectrode.

3. An image device comprising an elongated envelope, a photo-sensitivecathode within said envelope adapted to release an electron image in oneend of said envelope, a target electrode at the other end of saidenvelope, said target electrode being substantially larger than saidphotosensitive cathode, an apertured electrode intermediate said ends ofsaid envelope, means adjacent said one end of said envelope forselecting a portion of said electron image and directing said portionthrough said apertured electrode, and deflecting means adjacent saidother end of said envelope for defiecting said selected portion on tosaid target electrode.

4. An image device comprising an elongated envelope, a photo-sensitivecathode adapted to release an entire electron image in one end of saidenvelope, a target electrode at the other end of said envelope, saidtarget electrode being substantially larger than said photo-sensitivecathode, an apertured electrode intermediate said ends of said envelope,said apertured electrode being substantially the same size as saidphoto-sensitive cathode, deflection coils adjacent said one end of saidenvelope for selecting a portion of said electron image and deliectingsaid portion only through said apertured electrode, and detiection coilsadjacent said other end of said envelope for positioning said selectedportion on said target electrode.

5. An image device comprising, an elongated envelope, a photo-sensitivecathode upon which an optical image may be projected and from which anelectron image may be derived in one end of said envelope, a targetelectrode upon which an electron image may be projected and from whichan optical image may be derived in the other end of said envelope, anelectrode having an aperture therein intermediate said ends, meanswithin said envelope for accelerating electrons from said cathode tosaid target electrode, a focusing coil adjacent said one end of saidenvelope for focusing said electron image, a selection coil adjacentsaid one end of said envelope for selecting a portion of said electronimage and deflecting said portion only through said aperture, a focusingcoil adjacent said other end of said envelope for focusing said selectedelectron image, a positioning coil adjacent said other end of saidenvelope for positioning said selected electron image on said targetelectrode, means connected to said coils for varying said selectedportion and said position of said selected portion on said targetelectrode, and said apertured electrode being adapted to have apotential applied thereto that is negative with respect to the potentialapplied to said cathode whereby said electron image is cut olf from saidtarget electrode.

6. An image device, comprising an elongated envelope having an expandedend, a target electrode in said expanded end, a photo-emissive cathodein the other end of said envelope, an apertured electrode having asingle aperture therein intermediate said cathode and said targetelectrode, a first accelerating cylinder intermediate said cathode andsaid apertured electrode, a second accelerating cylinder intermediatesaid apertured electrode and said target electrode, a third electroncylinder and cone intermediate said second cylinder and said targetelectrode, a selection coil around the cathode end of said envelope, afocusing coil around said selection coil, a positioning coil around saidenvelope adjacent said expanded end, and a focusing coil around saidpositioning coil.

7. An image device as in claim 6 wherein said cathode and said aperturedelectrode are substantially the same size and extend across saidenvelope, and said target electrode is larger in size than said cathodeand extends across said expanded end of said envelope.

References Cited in the file of this patent UNITED STATES PATENTS2,163,545 Clothier et al. June 20, 1939 2,172,728 Bruche Sept. 12, 19392,283,383 McNaney May 15, 1942 2,365,006 Ricketts Dec. l2, 19442,603,418 Ferguson Iuly 15, 1952 2,730,708 McNaney Jan. 10, 1956

